We understand the importance of an area in our body when that area temporarily or permanently loses its function. The simplest example of this is our inability to smell or taste when we are sick. But we don’t have to wait to be sick to appreciate our unique features like these. With a little research, you can understand how extraordinary these features of ours seem to be.
Now, we will take a closer look at one of these features, which remains as a question mark in many people’s minds, ‘even though we have two eyes, there is only one image in front of us’. Without further ado, let’s get to the point.
The answer lies in the relationship between our brain and our eyes.
First of all, when we turn our eyes to a place or object, our brain processes that image thanks to our various perceptions and the information we store, and roughly we perform the act of seeing in this way. When we have two eyes, our brain has to deal with two separate images.
Don’t be misled by the fact that we say ‘separate’ here. Although our eyes transmit almost exactly the same image to the brain because they are close, there are differences between these images because their positions are different. We can think of them as complementing each other.
What happens to these two nearly identical images?
In the relevant part of our brain, the data received from our two eyes are processed, and in this way, we obtain a single image that is much more advanced than either eye alone can give.
So what exactly changes when this happens?
First of all, the fact that our two eyes create a common image allows us to obtain a three-dimensional image, which means we gain depth perception directly. In this way, you can measure the distance, width, length, etc. of something. we can understand better. This situation, which occurred at the point where the images presented by the two eyes overlapped, was a great advantage for survival, especially during the times when the ancestors had to hunt.
Another advantage of this view is that it provides a wide viewing angle.
Normally, when one eye is in the centre, our angle of vision is 95 degrees between our ear and the centre, and 60 degrees between our nose and the centre. In addition, we have a 60 degree angle of view upwards and 75 degrees downwards from the center.
This means that our vision angle of 155 degrees horizontally and 135 degrees vertically comes from only one eye. In addition, there is a blind spot of about 15 degrees in each eye, originating from the macula, the central region of the retina.
As we normally say, our single eye provides us with a 155-degree viewing angle. At double eye level, this angle increases to approximately 190 with the contribution of their position on our face.
Wouldn’t 155 degrees be enough?
Close your right eye and bring your right hand to a point where you can see it from the tip with your left eye. When you open your eyes, you can see how much difference this angle makes.
You can also ask a friend for help to see the difference in depth perception. To understand this, close your eyes and ask your friend to arrange random objects on the table. Then try to open only one eye and reach for those objects. Since there is no depth perception, your probability of missing with small differences will be quite high.
A few interesting facts:
- Chameleons, which can move their eyes independently, have a gigantic viewing angle of 180 horizontally and 90 vertically with one eye. Their unique eye structure enables them to switch between binocular and monocular vision shapes and obtain a panoramic view.
- Although our brain presents the image as ‘single’, there is a condition called diplopia that causes seeing objects as double.
See you in other content where we talk about the unique features of our body, which often do not attract our attention, although it happens before our eyes.
- Sources: Vedantu, Scientific American, Vision and Eye Health, AskNature, Top Doctors
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